If you have a HSA, you cannot have a medical FSA, but you can open a limited purpose flexible spending account (L-FSA) to use for dental and vision expenses. Dependent care and transportation and parking FSAs are still allowed. Consider a L-FSA if you contribute the annual maximum to your HSA. This will allow you to save your HSA dollars for future healthcare expenses, while putting pre-tax dollars in your L-FSA for current year vision and dental expenses.